1. Field of the Invention
The present invention relates to a gas control valve in a water heater and particularly to the connection structure of a unipolar overheat prevention terminal provided in the magnetic circuit of such a gas control valve.
2. Description of Related Art
An overheat prevention terminal in the magnetic circuit of a gas control valve in a storage type closed vessel gas water heater, for example, is generally mounted together with a thermocouple to the joint of a magnetic valve. More specifically, as shown in FIGS. 7 and 8, the joint 3a of the magnetic valve MV has an insertion recess 13 provided therein. The overheat prevention terminal 7 of bipolar type is fitted into the insertion recess 13 and secured with a retaining ring 15a before screwing a thermocouple TC on the recess 13.
However, for mounting the bipolar overheat prevention terminal 7 to the joint 3a of the magnetic valve MV, its insertion recess 13 has to be provided in the joint 3a which thus becomes bulky. Such a large joint is required and system body is made larger. Also, as the retaining ring 15a is used for anchoring the bipolar overheat prevention terminal 7, such problem or the like is caused that the number of components and thus the overall cost increase.
It is hence an object of the present invention to solve above-mentioned problems providing a gas control valve in a water heater which has a unipolar overheat prevention terminal provided between a burner flame detecting thermocouple and a gas shut off magnetic valve in the magnetic circuit.
For achieving the above object of the present invention, a gas control valve in a water heater as defined in claim 1 is characterized by a unipolar overheat prevention terminal provided between a burner flame detecting thermocouple and a gas shut off magnetic valve in the magnetic circuit.
The gas control valve in a water heater may be modified wherein the unipolar overheat prevention terminal is mounted in the main body of an ignition/extinction unit.
The gas control valve in a water heater may be modified wherein the unipolar overheat prevention terminal is supported by a retaining projection provided integrally on a cover of an ignition/extinction unit so that the unipolar overheat prevention terminal can hardly be detached.
As the gas control valve in a water heater has the unipolar overheat prevention terminal provided between the burner flame detecting thermocouple and the gas shut off magnetic valve in the magnetic circuit, the connection structure of the unipolar overheat prevention terminal can significantly be simplified. As a result, the unipolar overheat prevention terminal can be joined to the magnetic valve by only screwing the thermocouple.
As the gas control valve in a water heater allows the unipolar overheat prevention terminal to be mounted in the main body of the ignition/extinction unit, the joint of the magnetic valve remains smaller than that of any conventional valve. As the result, the system body can be made smaller.
As the gas control valve in a water heater allows the unipolar overheat prevention terminal to be supported by the retaining projection provided integrally on the cover of the ignition/extinction unit so that the terminal can hardly be detached, the unipolar overheat prevention terminal can remain connected even if the thermocouple is not connected. Accordingly, the connection of the unipolar overheat prevention terminal will be carried out with ease and improved in the working efficiency.